# A087301 (b-file synthesized from sequence entry)
2 2
3 3
4 20
5 70
6 564
7 3108
8 30624
9 230256
10 2705760
11 25771680
12 352805760
13 4067556480
14 63651813120
15 861371884800
16 15176802816000
17 235775183616000
18 4620563523072000
19 81032645804544000
20 1748700390205440000